To prepare it in sauce, you have to wash it at least 10x to remove all the salt--- which was used for keeping the meat fresh. As you would do with cleaning any fish, remove the scales. Then, boil the fish for about 30 minutes. Drain the water. What I like to do is to boil plain twin, yanm, and sweet potato with the cod, that way I don't have to add additional salt to them.
Some people would remove the skin and bones, but I love sucking on the bone because its a little salty and delicious. Add some oil to the pot, and place the fish with tomato, onions, green bell pepper, scallions, hot pepper. DO NOT ADD SALT!!! It's not acceptable to cook this fish salty! Add some Thyme, butter, and water. Lt it cook for about 45 min to 60 min.